http://orgprints.org/11825/ Agronomic and environmental factors explaining Grain Protein Content variability in organic winter wheat Casagrande, Marion David, Christophe Etienne, Catherine Makowski, David Valantin-Morison, Muriel Jeuffroy, Marie-Hélène Cereals, pulses and oilseeds A regional agronomic diagnosis was implemented to identify factors responsible for low values of Grain Protein Content (GPC) in a network of 35 organic winter wheat fields in South-Eastern France. The influence of water nutrition, radiation and temperature, weed density at flowering, nitrogen (N) status of crop at flowering and variety type were studied. Two statistical methods were used successively: classical linear regression and a mixing model approach based on a weighted sum of all possible linear combinations of explanatory variables. GPC was significantly related to variety type, crop N status and weed density. An analysis of variance showed that weed density was related to soil type and nitrogen supply. 2008 Conference paper, poster, etc. NonPeerReviewed rtf http://orgprints.org/11825/1/Casagrande_11825_ed.doc Casagrande, Marion; David, Christophe; Etienne, Catherine; Makowski, David; Valantin-Morison, Muriel and Jeuffroy, Marie-Hélène (2008) Agronomic and environmental factors explaining Grain Protein Content variability in organic winter wheat. Cultivating the Future Based on Science: 2nd Conference of the International Society of Organic Agriculture Research ISOFAR, Modena, Italy, June 18-20, 2008. http://orgprints.org/11825/http://orgprints.org/11825/1/